Bulletin of the American Physical Society
71st Annual Meeting of the APS Division of Fluid Dynamics
Volume 63, Number 13
Sunday–Tuesday, November 18–20, 2018; Atlanta, Georgia
Session L35: Geophysical Fluid Dynamics: General
4:05 PM–6:41 PM,
Monday, November 19, 2018
Georgia World Congress Center
Room: B407
Chair: Alfredo Pinelli, City University London
Abstract ID: BAPS.2018.DFD.L35.6
Abstract: L35.00006 : Gravity currents propagating over fixed beds of spherical particles*
5:10 PM–5:23 PM
Presenter:
Thomas Köllner
(University of California at Santa Barbara)
Authors:
Thomas Köllner
(University of California at Santa Barbara)
Alex Meredith
(University of Canterbury)
Claudia Cenedese
(Woods Hole Oceanographic Institution)
Roger Nokes
(University of Canterbury)
Eckart Meiburg
(University of California at Santa Barbara)
We investigate full-depth, saline lock-exchange gravity currents propagating over densely packed layers of spherical particles by laboratory experiments and direct numerical simulations. Our objective is to explore how the speed and composition of the current is influenced by this macro-rough bed.
Particle Tracking Velocimetry was employed to measure flow fields along the centerline of the flume while light attenuation was used to measure the spanwise averaged density field. Numerically, we solve the three-dimensional Navier-Stokes equations in the Boussinesq approximation, with an immersed boundary method to fully resolve the flow around each particle. The no-flux condition for the salinity at the particle surface is implemented by a volume of fluid approach. We vary the number of particle layers in the bed as well as the current height. For an increasing ratio of particle to current size, the current mixes more strongly with the bed fluid, so that it becomes progressively more diluted and its propagation speed is reduced. Simulations furthermore show that the dense fluid in the gravity current tail triggers a Rayleigh-Taylor instability within the porous bed.
*Financial support by the DFG under KO5515/1-1 and allocation TG-CTS150053 from XSEDE at the TACC is acknowledged.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2018.DFD.L35.6
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